Machines that utilize electric power often include a power generation system having a prime mover and a generator for generating the electrical power. The generator may be configured as an alternator that generates AC electrical power. In many instances, it is desirable to convert the AC electrical power into DC power through the use of a rectifier system.
A fault within an AC power generation system may result in the unbalanced generation of AC power that may damage components of the power generation system. In one example, certain types of faults may result in overheating of the windings of one or more phases within an alternator. Once a fault has been detected, a technician is often called upon to locate and fix the fault and return the machine to operation.
Systems have been developed to assist the technician by determining the type of fault that has occurred within the power generation system. For example, a sequence transformer system may be utilized to transform the output of the alternator into a positive sequence of phasors, a negative sequence of phasors, and a zero sequence of phasors. Properties of the sequences may be analyzed using symmetrical component analysis to determine the type of fault that has occurred. For example, certain properties may indicate a ground fault and other properties may indicate a fault between phases. In addition, other properties may indicate the number of phases between which a fault has occurred.
Knowing the type of fault may reduce the time required for a technician to locate and thus fix the fault. However, the sequence transformer system may not identify the location of the fault within the power generation system. As a result, a technician may be required to spend a considerable amount of time attempting to identify the specific location of the fault.
Relay protection systems may be used to determine whether a fault has occurred in an electrical component and to shut down the current to the component or other systems to protect the component and the systems. Differential relays often operate by comparing the input current to the output current and triggering the relay if the difference exceeds a threshold for a predetermined time. The difficulty in using a relay to monitor the operation of a rectifier is increased due to the different forms of input and output current (i.e., AC current and DC current, respectively).
U.S. Pat. No. 7,994,798 discloses a power generation system that includes an alternator and a rectifier for converting AC power to DC power. Current sensors may be used to measure the DC current that is provided to the electric motors of a traction system. A system is provided to test the current sensors by comparing a measured current with a stored profile. The test results may be used to assist in determining the location of a fault.
The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Thus, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described herein are defined by the appended claims.